HARRISBURG, Pa. (AP) – Democratic Gov. Tom Wolf’s environmental protection secretary has resigned after Wolf’s office said it was looking into an email the official sent to advocacy groups from a private email address.

Wolf confirmed John Quigley’s resignation in a brief interview Friday but didn’t explain the reasons behind it. He says Quigley did a fine job.

The resignation came hours after the governor’s office disclosed its inquiry into the email.

A state lawmaker, Democratic Sen. John Yudichak, had said earlier that “serious concerns” had been raised about Quigley’s conduct.